Aralkoxy and aryloxyalkoxy kojic acid derivatives

ABSTRACT

This invention relates to substituted aralkoxy and aryloxyalkoxy kojic acid derivatives, which are useful as leukotriene D 4  (LTD 4 ) inhibitors and therefore useful in the treatment of allergies, inflammatory conditions, and coronary vasoconstriction.

This is a division of application Ser. No. 894,591 filed Aug. 8, 1986now U.S. Pat. No. 4,705,871 which is a division of application Ser. No.629,916 filed July 11, 1984 now U.S. Pat. No. 4,644,071.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

This invention in its broadest aspect relates to inhibitors of metabolicpathways. In particular, the invention relates to novel compounds ofFormula I, which are inhibitors of leukotriene D₄ (LTD₄) and whichtherefore are useful to prevent or allleviate the symptoms associatedwith LTD₄, such as allergic reactions, particularly asthma, see M.Griffin et al., N. Engl. J. Med., 308, 436 (1983); inflammatoryconditions; and coronary vasoconstriction.

LTD₄ is a product of the 5-lipoxygenase pathway and is the major activeconstituent of slow reacting substance of anaphylaxis (SRS-A), a potentbronchoconstrictor that is released during allergic reactions. See R. A.Lewis and K. F. Austen, Nature, 293, 103-108 (1981). When administeredto humans and guinea pigs, LTD₄ causes bronchoconstriction by twomechanisms: (1) directly by stimulating smooth muscle; and (2)indirectly through release of thromboxin A₂, which causes contraction ofrespiratory smooth muscle. Because antihistamines are ineffective in themanagement of asthma, SRS-A is believed to be a mediator of thebronchoconstriction occurring during an allergic attack. LTD₄ may alsobe involved in other inflammatory conditions such as rheumatoidarthritis. Furthermore, LTD₄ is a potent coronary vasoconstrictor andinfluences contractile force in the myocardium and coronary flow rate ofthe isolated heart. See F. Michelassi et al., Science, 217, 841 (1982);J. A. Burke et al., J. Pharmacol. and Exp. Therap., 221, 235 (982).

(b) Prior Art

A number of aryloxyalkoxy benzopyrans and benzopyranones have beendisclosed as useful leukotriene inhibitors. See, e.g., U.S. Pat. Nos.4,238,495, 4,213,903, 4,006,245, and 3,953,604; British Pat. No.1,291,864; and R. A. Appleton et al., J. Med. Chem., 20, 371-379 (1977).The compounds of this invention represent the first class of LTD₄inhibitors in which a pyranone moiety is not ring-fused to a benzenering and is instead attached directly to an aryloxyalkoxy or aralkoxysubstituent.

SUMMARY OF THE INVENTION

The invention relates to compounds of Formula I: ##STR1## wherein R¹ is:##STR2## wherein R² is: (a) CH₂ OH;

(b) CH═O; or

(c) COOR⁶ ;

Wherein R³ is:

(a) hydrogen;

(b) alkyl of 1 to 6 carbon atoms, inclusive; or

(c) alkenyl of 2 to 6 carbon atoms, inclusive;

wherein R⁴ is:

(a) hydrogen; or

(b) hydroxy;

wherein R⁵ is:

(a) hydrogen; or

(b) alkanoyl of 2 to 6 carbon atoms, inclusive;

wherein R⁶ is:

(a) hydrogen;

(b) alkyl of 1 to 6 carbon atoms, inclusive;

(c) alkali metal ion; or

(d) R⁷ R⁸ R⁹ R¹⁰ N⁺ ;

wherein R⁷, R⁸, R⁹, and R¹⁰, each being the same or different, are:

(a) hydrogen; or

(b) alkyl of 1 to 6 carbon atoms, inclusive;

wherein m is an integer from 1 to 10, inclusive.

Examples of alkyl of 1 to 6 carbon atoms, inclusive, are methyl, ethyl,propyl, butyl, pentyl, hexyl, and the isomeric forms thereof, generallyreferred to as alkyl.

Examples of alkenyl of 2 to 6 carbon atoms, inclusive, are ethenyl,1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl,2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenhyl,4-hexenyl, 5-hexenyl, and the isomeric forms thereof.

Examples of alkanoyl of 2 to 6 carbon atoms, inclusive, are acetyl,propanoyl, butanoyl, pentanoyl, hexanoyl, and the isomeric formsthereof.

Examples of pharmaceutically acceptable alkali metal ions are lithium,sodium, and potassium.

DESCRIPTION OF THE INVENTION

The compounds of this invention may be prepared by any of severalmethods known to those skilled in the art. For example, the particularsequence of reactions joining the aromatic rings through the linkingalkylene bridge may be selected for synthetic convenience or formaximization of yields. The following Schemes illustrate methods used toprepare the compounds of this invention. Compounds are typicallypurified by recrystallization from suitable solvents or bychromatography. Unless otherwise specified, the various substituentsillustrated in the Schemes are defined as for Formula I, above.

Scheme A illustrates the preferred method used to prepare the compoundsof this invention.

SCHEME A

Hydroxypyranones of Formula II react readily with compounds of FormulaIII (where X represents a halogen, preferably bromine) to form thecompounds of this invention, Formula I. A preferred method involvesstirring compounds II and III in dimethylformamide in the presence of abase, such as potassium carbonate. By way of illustrating that theparticular sequence of reactions may be varied, compounds of Formula Iwhere R¹ is an aryloxy function may be prepared by first attaching thealkylene chain to the hydroxypyranone moiety and then by using themethod illustrated in Scheme A to attach that adduct to the R¹ moiety.Where necessary, substituents R² may be modified as part of thepreparation of starting materials of Formula II. For example, usingmethods known to those skilled in the art, kojic acid (Formula II, R² isCH₂ OH) may be protected and oxidized to the corresponding carboxylicacid and then converted to esters (Formula II, R² is COOAlkyl). SchemesB and C illustrate several methods for modifying R² after compounds ofFormula I have been prepared. ##STR3##

Scheme B Illustrates methods for converting hydroxymethyl compounds ofFormula IV (that is, Formula I where R² is CH₂ OH) to other compounds ofthis invention.

SCHEME B

Mild oxidation of alcohols of Formula IV affords correspondingaldehydes, Formula V. A preferred mild oxidation method employspyridinium chlorochromate in dichloromethane at room temperature.Harsher oxidation conditions convert alcohols of Formula IV to thecorresponding carboxylic acids, Formula VI. A preferred oxidation methodemploys Jones reagent (an adduct of chromic anhydride and aqueoussulfuric acid used in acetone solution). A similar oxidation ofaldehydes, Formula V, will also afford carboxylic acids of Formula VI.Esters of Formula VII may then be prepared from the carboxylic acids, V,by the usual methods known to those skilled in the art. For example, apreferred method for preparing methyl esters employs methyl iodide indimethylformamide in the presence of potassium carbonate, and typicallyalso in the presence of 4A molecular sieves.

Scheme C illustrates methods used to prepare various other carboxylicacid derivatives of Formula I (that is, where R² is COOR⁶) from estersof Formula VII (prepared directly as in Scheme A or indirectly as inScheme B). ##STR4##

SCHEME C

Saponification of esters, VII, affords metal ion salts of Formula VIII(where M⁺ is an alkali metal ion). A preferred saponification methodemploys three-fold sodium hydroxide in 50% (by volume) aqueous ethanolstirred at room temperature. Salts VIII may be converted to the freecarboxylic acids, VI, either in situ or after isolation by addition ofdilute aqueous mineral acid to solutions of the salts. The carboxylicacids, VI, may be converted to various amine salts (Formula VIII, whereM⁺ represents R⁷ R⁸ R⁹ R¹⁰ N⁺) by addition of appropriate organic aminesor reconverted to various metal ion salts (Formula VIII, where M⁺represents a metal cation) by addition of inorganic bases, such assodium or potassium hydroxide. Ion exchange affords another method forforming such salts from compounds of Formula VI or VIII.

The compounds of this invention may also be converted to otherderivatives. Scheme D illustrates one such conversion.

SCHEME D

Catalytic hydrogenation of compounds of Formula IX, where R⁶ representseither hydrogen of lower alkyl, affords cyclic ethers of Formula X. Apreferred hydrogenation method employs hydrogen gas at 2 psi pressureand 5% ##STR5## palladium on carbon as catalyst, with an alcohol such asethanol as solvent. Reduced compounds such as those of Formula Xgenerally retain at least some of the LTD₄ inhibitory activity of theparent compounds.

The preferred embodiments of this invention include compounds of thefollowing general structure, Formula XI. ##STR6## More specifically, thepreferred embodiments include compounds of Formula XI wherein R² is CH₂OH, CH═O, or COOR⁶ ; wherein R³ is lower alkyl (that is consisting of 1to 6 carbon atoms, inclusive); wherein R⁴ and R⁵ are both hydrogen, orR⁴ is hydroxy and R⁵ is acetyl; wherein R⁶ is hydrogen or lower alkyl;and wherein m is an integer of 1 to 10, inclusive.

The most preferred embodiments of this invention include compounds ofthe following general structure, Formula XII. ##STR7## Morespecifically, the most preferred embodiments include compounds ofFormula XII wherein R³ is lower alkyl (that is, consisting of 1 to 6carbon atoms, inclusive); and wherein m is an integer of 3 to 7,inclusive.

The compounds of this invention exhibited antiallergy activity in guineapigs, as indicated by antagonism in vitro (isolated ileum segments) ofLTD₄ -induced smooth muscle contractions and by antagonism in vivo ofLTD₄ -induced bronchoconstriction. The antiallergy activity of thecompounds of this invention illustrated in the examples was tested bythe following methods.

Antagonism of LTD₄ -induced Smooth Muscle Contractions

Segments of ileum tissue isolated from guinea pigs were mounted in amodified Tyrode solution (8.046 g/l of sodium chloride, 0.200 g/l ofpotassium chloride, 0.132 g/l of calcium chloride monohydrate, 0.106 g/lof magnesium chloride hexahydrate, 1.00 g/l of sodium bicarbonate, 0.058g/l of sodium dihydrogen phosphate, and 1.00 g/l of dextrose) containing0.1 mcg/ml atropine sulfate and 1.0 mcg/ml of pyrilamine maleate andaerated at 37° C. with 95% oxygen and 5% carbon dioxide. The tissuesegments were stimulated with two or more concentrations of either LTD₄or bradykinin triacetate (agonists), producing reproducible musclecontractions. The control solution was replaced by a solution orsuspension of test compound (1.0×10⁻⁵ M) and incubated for 30 minutes.Each agonist was again introduced to the appropriate solutions andincreased doses were added, if necessary, until conntractions wereapproximately equal to those of the previously determined controls oruntil excessive quantities of agonist were added. For each combinationof test compound and agonist, the following dose ratio was calculated:the ratio of agonist concentration in the presence of test compound tothe agonist concentration in the absence of test compound that willproduce the same contractile response. A concentration of test compoundwas considered active if it produced a dose ratio against LTD₄significantly (P<0.05) greater than a dose ratio obtained in a series ofblank treatment tests. (Duplicate tests were conducted for eachconcentration of test compound, and third tests were conducted if thefirst two tests were incosistent.) Compounds that were active againstLTD₄ but not against bradykinin triacetate were considered selectiveLTD₄ antagonists.

A further measure of receptor affinity, PA₂, was also determined forselective LTD₄ antagonists. A pA₂ value is defined as the negativelogarithm of the molar concentration of the antagonist which produces adose ratio of 2. The pA₂ values were calculated by the method ofArunlakshana and Schild, Br. J. Pharmacol., 2, 189 (1947), using Schildplot slopes constrained to -1. See R. J. Tallarida and R. B. Murray,Manual of Pharmacologic Calculations with Computer Programs (New York:Springer-Verlag, 1981), pp. 33-35.

Antagonism of LTD₄ -induced Bronchoconstriction

Fasted adult male Hartley guinea pigs weighing 300 to 350 grams wereused in this assay. All test animals were pretreated with propranololand pyrilamine to block the bronchoconstrictive effects of endogenousepinephrine and histamine, respectively, and with indomethacin to blockthe synthesis of thromboxane A₂. The animals were anesthetized withpentobarbital and attached to a rodent respirator. Continuousmeasurements of intratracheal insufflation pressure were obtainedthrough an intratracheal pressure transducer. After a baseline recordwas obtained, LTD₄ (200 ng) was administered intravenously andagonist-induced changes in intratracheal insufflation pressure weremeasured. Compounds which antagonize the direct component of LTD₄ actionon respiratory smooth muscle inhibit intratracheal insufflation pressureincreases caused by LTD₄. To determine the effect of test compounds onLTD₄ -induced bronchoconstriction, the compounds were administered tothe animals either intravenously (10 mg per kg body weight) orintragastrically (100 mg per kg of body weight) at an appropriateinterval prior to the LTD₄ challenge. Test compounds were rated activeif intratracheal insufflation pressure was significantly (P<0.05)reduced relative to vehicle control animals, as assessed by a Student'sone-tail t-test.

By virtue of the activity as LTD₄ antagonists, the compounds of FormulaI are useful in treating asthma and other allergic conditions,inflammation, and coronary vasoconstriction in mammals. A physician orveterinarian of ordinary skill can readily determine whether a subjectexhibits the conditions. The preferred utility relates to treatment ofasthma. Regardless of the route of administration selected, thecompounds of the present invention are formulated into pharmaceuticallyacceptable dosage forms by conventional methods known to those skilledin the art. The compounds may be formulated using pharmacologicallyacceptable base addition salts. Moreover, the compounds or their saltsmay be used in a suitable hydrated form.

The compounds can be administered in such oral dosage forms as tablets,capsules, pills, powders, or granules. They may also be administeredintravascularly, intraperitoneally, subcutaneously, or intramuscularly,using forms known to the pharmaceutical art. In general, the preferredform of administration is oral. An effective but non-toxic quantity ofthe compound is employed in treatment. The dosage regimen for preventingor treating the particular affiction with the compounds of thisinvention is selected in accodance with a variety of factors, includingthe type, age, weight sex, and medical condition of the patient; theseverity of the condition; the route of administration; and theparticular compound employed. An ordinarily skilled physician orveterinarian can readily determine and prescribe the effective amount ofthe drug required to prevent or arrest the progress of the condition. Inso proceeding, the physician or veterinarian could employ relatively lowdoses at first and subsequently increase the dose until a maximumresponse is obtained. Dosages of the compounds of the invention areordinarily in the range of 0.1 to 10 mg/kg up to about 100 mg/kg orally.

The following examples further illustrate details for the preparation ofthe compounds of this invention. The invention, which is set forth inthe foregoing disclosure, is not to be construed or limited either inspirit or in scope by these examples. Those skilled in the art willreadily understand that known variations of the conditions and processesof the following preparative procedures can be used to prepare thesecompounds. All temperatures are degrees Celsius unless otherwise noted.

PREPARATION OF STARTING MATERIALS AND INNTERMEDIATES Preparation 15-benzyloxy-2-(hydroxymethyl)-4H-pyran-4-one ##STR8## To a stirredsolution of 17 g (0.12 mole of kojic acid and 5.1 g (0.13 mole) ofsodium hydroxide in 190 ml of 10:1 (by volume) methanol-water was addeddropwise 17.5 g (0.14 mole) of benzyl chloride. After 4.5 hours atreflux, the mixture was allowed to cool and was poured into 200 ml ofice-water. The resultant solid was collected, washed with water, anddried, giving 22.4 g of analytically pure title compound, m.p.128°-130°.

Analysis. Calcd. for C₁₃ H₁₂ O₄ : C, 67.23; H, 5.21. Found: C, 67.24; H,5.05.

Preparation 2 methyl 5-benzyloxy-4-oxo-4H-pyran-2-carboxylate ##STR9##To a solution of 35.5 g (0.15 mole) of5-benzyloxy-2-(hydroxymethyl)-4H-pyran-4-one (prepared according toPreparation 1) in 2.6 l of acetone was added 143 ml (ca. 0.383 mole) of2.68M Jones reagent at 0°. The mixture was heated at room temperaturefor about one hour, then placed on a steam bath for a further ten hours.The reaction was quenched with 250 ml of isopropyl alcohol, insolublechromium salts were removed by filtration, and the filtrate wasconcentrated in vacuo to dryness. The crude intermediate was dissolvedin aqueous sodium bicarbonate and filtered to remove insolubles. Thefiltrate was saturated with sodium chloride and acidified (ca. pH 2)with dilute hydrochloric acid, giving 31.0 g of the intermediatecarboxylic acid. This interediate was converted to the title esterwithout further purification by the following method. A mixture of 28.3g (ca. 0.12 mole) of the intermediate, 31.8 g (0.23 mole) of anhydrouspotassium carbonate, and 21.2 g (0.15 mole) of methyl iodide in 150 mlof dimethylformamide was stirred for ca. 16 hours and then concentratedin vacuo. The residue was dissolved in ethyl acetate, and againfiltered. The filtrate was concentrated and the resultant solid waschromatographed on silica gel using ethyl acetate-hexane as eluent. Thetitle compound (25.2 g) was isolated as an analytically pure solid, m.p.134°-135.5°.

Analysis. Calcd. for C₁₄ H₁₂ O₅ : C, 64.61; H, 4.65. Found: C, 64.57; H,4.59.

Preparation 3 methyl 5-hydroxy-4-oxo-4H-pyran-2-carboxylate ##STR10##The title product of Preparation 2 (24.0 g, 0.092 mole) was dissolved ina mixture of 360 ml each of tetrahydrofuran and methanol, and thenhydrogenated at room temperature using 2 psi of hydrogen and 5%palladium on barium sulfate as catalyst. Insolubles were removed byfiltration and the filtrate was concentrated in vacuo to a solid thatwas recrystallized from acetone, giving 16.6 g (in two crops) ofanalytically pure title compound,

m.p. 183.5°-185.5°.

Analysis. Calcd. for C₇ H₆ O₅ : C, 49.42; H, 3.55. Found (first crop):C, 49.31; 3.22. Found (second crop): C, 49.31; 3.31.

Preparation 4 4-(5-bromopentoxy)-2-hydroxy-3-propylacetophenone##STR11## A mixture of 120 g (0.61 mole) of2,4-dihydroxy-3-propylacetophenone, 284 g (1.23 mole) of1,5-dibromopentane, and 128 g (0.93 mole) of anhydrous potassiumcarbonate in 2 l of dimethylformamide was stirred vigorously for sixhours at room temperature. Insolubles were removed by filtration and thefiltrate was concentrated in vacuo. The oily residue was redissolved in1 l of 10% ethyl acetate-hexane, refiltered, concentrated to dryness,and purified by high performance chromatography on silica gel. The titlecompound was obtained as 128 g of an analytically pure colorless oil.

Analysis. Calcd. for C₁₆ H₂₃ O₃ Br: C, 55.99; H, 6.75; Br, 23.28. Found:C, 55.72; H, 6.85; Br. 23.51.

Preparation 5 1-(5-bromopentoxy)-2-propylbenzene ##STR12## A mixture of90 g (0.66 mole) of 2-propylphenol, 300 g (1.30 mole) of1,5-dibromopentane, 120 g of anhydrous potassium carbonate, and 9 g ofsodium iodide in 1.2 l of methyl ethyl ketone was stirred at reflux fortwo days. After cooling, the mixture was filtered to remove insolublesand the filtrate was concentrated in vacuo. The residue was distilledunder vacuum to give 120 g of the title compound as an analytically pureoil, b.p. 123°-125° at 0.1 mm Hg.

Analysis. Calcd. for C₁₂ H₂₁ OBr: C, 58.95; H, 7.42; Br, 28.02. Found:C, 58.90; H, 7.43; Br, 27.75.

Preparation 6 2-(3-bromopropoxy)naphthalene ##STR13## A mixture of 14.5g (0.1 mole) of 2-naphthol, 30.3 g (0.15 mole) of 1,3-dibromopropane, 15g of anhydrous potassium carbonate, and 1 g of sodium iodide in 125 mlof methyl ethyl ketone was stirred at reflux for one day. After cooling,the mixture was filtered to remove insolubles and the filtrate wasconcentrated in vacuo to dryness. The residue was dissolved indichloromethane, washed twice with 10% aqueous sodium hydroxide, andredried thoroughly in vacuo. The residue was dissolved in hot pentaneand filtered hot, and the filtrate was then concentrated under a streamof nitrogen and cooled in a refrigerator, giving the title compound,m.p. 53°-55°.

Analysis. Calcd. for C₁₃ H₁₃ OBr: C, 58.89; H, 4.94; Br, 30.14. Found:C, 59.27; H, 4.91; Br, 29.49.

Preparation 7 2-(2-bromoethyl)naphthalene ##STR14## To a solution of 25g (145 mmole) of 2-(2-naphthyl)ethanol and 67.9 g (259 mmole) oftriphenylphosphine in 200 ml of benzene was added in portions 46.1 g(259 mmole) of N-bromosuccinimide. A temperature of 45°-50° wasmaintained by cooling the reaction mixture as needed in an ice bath.After the mixture was poured into 750 ml of hexane and filtered, thefiltrate was diluted with an additional 400 ml of hexane and allowed tostand overnight. The solution was concentrated to dryness and theresultant solid was purified by chromatography on silica gel. The titlecompound (30.5 g), m.p. 55°-57°, was homogeneous by thin-layerchromatography (5%, 10%, and 15% by volume ethyl acetate-hexane onsilica gel plates), and was used in subsequent reactions without furtherpurification. Preparation 82-bromoethyl-1,2,3,4-tetrahydro-2-naphthalene ##STR15## The titlecompound was prepared by the method of Preparation 7 using1,2,3,4-tetrahydro-2-naphthalenylmethanol in place of2-(2-naphthyl)ethanol, except that only slight molar excesses oftriphenylphosphine and N-bromosuccinimide were required. Afterchromatography, the title compoundd was further purified by distillationat 95° at 0.2 mm Hg pressure, giving 5.5 g of an analytically pure oil.

Analysis. Calcd. for C₁₁ H₁₃ Br: C, 58,69; H, 5.82; Br, 35.49. Found: C,58.53; H, 6.00; Br, 34.83.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 15-[5-(4-acetyl-3-hydroxy-2-propylphenoxy)pentoxy]-2-(hydroxymethyl)-4H-pyran-4-one##STR16## A mixture of 11.4 g (33.2 mmole) of the title product ofPreparation 4, 3.78 g (26.6 mmole) of kojic acid, and 8.3 g (60 mmole)of anhydrous potassium carbonate in 150 ml of dimethylformamide wasstirred at room temperature for three days. After removing insolubles byfiltration, the mixture was concentrated in vacuo and triturated with300 ml of ethyl acetate. Upon refiltering, the solution was concentratedto dryness, and the residue was dissolved in 50 ml of hot ethyl acetate,filtered, and concentrated. Purification by high performancechromatography on silica gel (using ethyl acetate as eluent) afforded3.0 g of the title compound, m.p. 94°-95°, as an analytically puresolid.

Analysis. Calcd. for C₂₂ H₂₈ O₇ : C, 65.33; H, 6.98. Found: C, 65.19; H,7.01.

EXAMPLE 2 methyl5-[5-(4-acetyl-3-hydroxy-2-propylphenoxy)pentoxy]-4-oxo-4H-pyran-2-carboxylate##STR17## A mixture of 3.43 g (10 mmole) of the title product ofPreparation 4, 1.70 g (10 mmole) of the title product of Preparation 3,and 2.76 g (20 mmole) of anhydrous potassium carbonate in 75 ml ofdimethylformamide was stirred at 70° for one day. After removinginsolubles by filtration, the mixture was concentrated in vacuo to anoily residue, which was dissolved in ethyl acetate, filtered, andreconcentrated. Purification by high performance chromatography onsilica gel (using 25% by volume ethyl acetate-dichloromethane as eluent)afforded 2.0 g of the title compound, m.p. 95°-97°, as an analyticallypure solid.

Analysis. Calcd. for C₂₃ H₂₈ O₈ : C, 63.88; H, 6.53. Found: C, 63.89; H,6.54.

EXAMPLE 35-[5-(4-acetyl-3-hydroxy-2-propylphenoxy)pentoxy]-4-oxo-4H-pyran-2-carboxylicacid ##STR18## To a solution of 910 mg (2.1 mmole) of the title productof Example 2 in 15 ml of ethanol was added 160 mg (4 mmole) of sodiumhydroxide dissolved in 15 ml of water. The mixture was stirred overnightand then acidified (ca. pH 2) with dilute hydrochloric acid. Theresulting precipitate was collected by filtration, washed thoroughlywith water, and dried under reduced pressure to give 680 mg ofanalytically pure title compound.

Analysis. Calcd. for C₂₂ H₂₆ O₈ : C, 63.00; H, 6.49. Found: C, 62.86; H,6.43.

EXAMPLE 45-[5-(2-propylphenoxy)pentoxy]-2-(hydroxymethyl)-4H-pyran-4-one##STR19## The title compound (4.2 g) was prepared by the method ofExample 1, except that the title product of Preparation 5 (7.8 g, 27mmole) was used instead of the title product of Preparation 4.

Analysis. Calcd. for C₂₀ H₂₆ O₅ : C, 69.34; H, 7.56. Found: C, 69.34; H,7.59.

EXAMPLE 5 4-oxo-5-[5-(2-propylphenoxy)pentoxy]-4H-pyran-2-carboxaldehyde##STR20## To a stirred solution of 4.44 g (20.6 mmole) of pyridiniumchlorochromate in 50 ml of dichloromethane was added 3.46 g (10 mmole)of the title alcohol of Example 4 dissolved in 50 ml of dichloromethane.The resulting slurry was stirred at room temperature for twenty-fourhours, then diluted with 100 ml of diethyl ether. The insolubles wereremoved by decanting and the supernatant was concentrated in vacuo.Purification by column chromatography afforded 1.4 g of the titlecompound, m.p. 95°-96°.

Analysis. Calcd. for C₂₀ H₂₄ O₅ : C, 69.75; H, 7.02. Found: C, 69.52; H,7.04.

EXAMPLE 6 4-oxo-5-[5-(2-propylphenoxy)pentoxy]-4H-pyran-2-carboxylicacid monohydrate ##STR21## To a stirred solution 3.53 g (10.2 mmole) ofthe title alcohol of Example 4 in 100 ml of acetone was added dropwise22.7 ml (ca. 20.4 mmole) of 0.9M Jones reagent. The solution was warmedto 50° and an additional 11.4 ml (10.2 mmoles) of Jones reagent wasadded. After five hours at room temperature the reaction was quenchedwith 40 ml of isopropyl alcohol. The insolubles were removed bydecanting and the supernatant was concentrated in vacuo. The residue wastriturated with ethyl acetate and filtered, and the filtrate wasreconcentrated. Recrystallization from ethyl acetate-hexane (2:1 byvolume) afforded 1.8 g of the title compound as the monohydrate.

Analysis. Calcd. for C₂₀ H₂₄ O₆.H₂ O: C, 63,49; H, 6.92. Found: C,63.58; H, 6.52.

EXAMPLE 7 methyl4-oxo-5-[5-(2-propylphenoxy)pentoxy]-4H-pyran-2-carboxylate ##STR22## Asolution of the title product of Example 7 (1.14 g, 3 mmole) indimethylformamide was dried overnight by stirring with 4A molecularsieves. Anhydrous potassium carbonate (0.55 g, 4 mmole) and methyliodide (0.43 g, 3 mmole) were added, and the mixture was stirred at roomtemperature for thirty-six hours. Insolubles were removed by filtrationand the filtrate was concentrated in vacuo to dryness. The residue waspurified by column chromatography on silica gel (using 25% by volumeethyl acetate-hexane as eluent), affording 815 mg of analytically puretitle compound, m.p. 49°-50°.

Analysis. Calcd. for C₂₁ H₂₆ O₆ : C, 67.36; H, 7.02. Found: C, 67.20; H,7.21.

EXAMPLE 8methyl-5-[3-(2-naphthalenyloxy)propoxy]-4-oxo-4H-pyran-2-carboxylate##STR23## A mixture of 1.70 g (10 mmole) of the title product ofPreparation 3, 2.65 g (10 mmole) of the title product of Preparation 6,and 2.76 g (20 mmole) of anhydrous potassium carbonate in 50 ml ofdimethylformamide was stirred for three days at room temperature. Thetitle compound, m.p. 90°-91°, was purified and isolated (1.34 g) by themethod described in Example 2, except that the chromatographic eluentwas 50% by volume ethyl acetate-Skellysolve B.

Analysis. Calcd. for C₂₀ H₁₈ O₆ : C, 67.79; H, 5.12. Found: C, 67.56; H,5.06.

EXAMPLE 9 sodium5-[3-(2-naphthalenyloxy)propoxy]-4-oxo-4H-pyran-2-carboxylate dihydrate##STR24## To a solution of 300 mg (0.85) mmole) of the title product ofExample 8 in 6 ml of ethanol was added 100 mg (2.5 mmole) of sodiumhydroxide dissolved in 6 ml of water. The mixture was stirred overnightand the resultant crystalline solid was collected by filtration. Dryingunder reduced pressure at 80° afforded 116 mg of analytically pure titlecompound as the dihydrate.

Analysis. Calcd. for C₁₉ H_(15L) O₆ Na.2H₂ O: C, 57.29; H. 4.81. Found:C, 57.47; H, 4.25.

EXAMPLE 10 methyl5-[2-(2-naphthalenyl)ethoxy]-4-oxo-4H-pyran-2-carboxylate ##STR25## Amixture of 1.70 g (10 mmole) of the title product of Preparation 3, 2.83g (12 mmole) of the title product of Preparation 7, and 2.76 g (20mmole) of anhydrous potassium carbonate in 50 ml of dimethylformamidewas stirred at 80° for one day. The title compound, m.p. 129°-130°, waspurified and isolated (530 mg) by the method described in Example 2,except that (1) the initially isolated crude residue was dissolved bytrituration with 50% by volume ethyl acetate-ethanol and (2) thechromatographic eluent was 40% by volume ethyl acetate-hexane.

Analysis. Calcd. for C₁₉ H₁₆ O₅ : C, 70.36; H, 4.97. Found: C, 70.74; H,5.28.

EXAMPLE 11 sodium5-[2-(2-naphthalenyl)ethoxy]-4-oxo-4H-pyran-2-carboxylate dihydrate##STR26## The title compound, isolated as the dihydrate, was prepared bythe method of Example 9 using 205 mg (0.63 mmole) of the title productof Example 11 instead of the title product of Example 8.

Analysis. Calcd. for C₁₈ H₁₂ O₅ Na.2H₂ O: C, 58.70; H, 4.65. Found: C,58.99; H, 4.23.

EXAMPLE 12 methyl5-(1,2,3,4-tetrahydro-2-naphthalenylmethoxy)-4-oxo-4H-pyran-2-carboxylate##STR27## The title compound is prepared by the method described inExample 2 using the title product of Preparation 8 instead of the titleproduct of Preparation 4. EXAMPLE 13 sodium5-(1,2,3,4-tetrahydro-2-naphthalenylmethoxy)-4-oxo-4H-pyran-2-carboxylate##STR28## The title compound is prepared by the method of Example 9using the title product of Example 12 instead of the title product ofExample 8. EXAMPLE 14 methyl5-[5-(4-acetyl-3-hydroxy-2-propylphenoxy)pentoxy]tetrahydro-4-hydroxy-2H-pyran-2-carboxylate##STR29## The title product of Example 2 (840 mg, 1.96 mmole) wasdissolved in 110 ml ethanol, and then hydrogenated at room temperatureusing 2 psi of hydrogen and 5% palladium on carbon as catalyst.Insolubles were removed by filtration and the filtrate was concentratedin vacuo, and the incompletely reduced residue (as determined by nmr in(CD₃)₂ SO) was again hydrogenated. Purification by high performancechromatography on silica gel (using 30% by volume acetone-hexane)afforded 145 mg of the title compound as an oil. Spectral data indicatecomplete reduction of the pyranone moiety to the hydroxy-substitutedcyclic ether.

¹³ C nmr (CDCl₃):

carbonyl carbon: 203.1 (s) and 171.3 (s) ppm aromatic ring carbon: 163.2(s), 162.2 (s), 130.3 (d),

118.3 (s), 114.2 (s), and 102.9 (d) ppm CH₂ -O and CH-O carbon: 75.0(d), 73.2 (d), 69.1 (t),

68.1 (t), 67.3 (d), and 65.0 (t) ppm methoxy carbon: 52.1 (q) ppmremaining aliphatic carbon: 33.0, 29.5, 29.0, 26.1,

24.4, 22.8, 22.0, and 14.2 ppm proton nmr (CDCl₃): δ (ppm) 0.94 (t, 3H,propyl CH₃); 1.1-2.6 (m's, 12 H, CH₂ 's); 2.55 (s, 3H, acetyl CH₃);3.3-4.4 (m's, ca. 9H plus H₂ O, O-CH₂ 's and O-CH's); 3.78 (s, 3H,methoxy CH₃); 6.34 and 7.56 (aromatic CH's)

Infrared: two carbonyl absorptions--1625, 1748 cm⁻¹

Analysis. Calcd. for C₂₃ H₃₄ O₈ : C, 62.99; H, 7.82. Found: C, 62.15; H,7.91.

EXAMPLE 155-[5-(4-acetyl-3-hydroxy-2-propylphenoxy)pentoxy]tetrahydro-4-hydroxy-2H-pyran-2-carboxylicacid ##STR30##

To a solution of 144 mg (0.33 mmole) of the title product of Example 4in 3 ml of methanol was added 3.3 ml (1.0 mmole) of 0.3M sodiumhydroxide. After 90 minutes the solution was concentrated to removeexcess methanol and ethyl acetate was added. After the mixture wasacidified carefully with dilute hydrochloride acid, the ethyl acetatelayer was separated and the aqueous layer washed with additionalportions of ethyl acetate. The combined organic layers were dried oversodium sulfate, filtered, and concentrated to dryness. Mass spectrometryindicated a molecular weight of 424, corresponding to the expected titlecompound.

¹³ C nmr (CDCl₃): nearly identical to that of ester of Example 14,except for loss of methoxy carbon and shift of carboxyl carbon at 171.3ppm to 174.4 ppm.

What is claimed is:
 1. A compound of the formula: ##STR31## wherein R²is: (a) CH₂ OH;(b) CH═O; or (c) COOR⁶ ;wherein R⁶ is: (a) hydrogen; (b)alkyl of 1 to 6 carbon atoms, inclusive; (c) alkali metal ion; or (d) R⁷R⁸ R⁹ R¹⁰ N⁺ ;wherein R⁷, R⁸, R⁹, and R¹⁰, each being the same ordifferent, are: (a) hydrogen; or (b) alkyl of 1 to 6 carbon atoms,inclusive;wherein m is an integer from 1 to 10, inclusive.
 2. A compoundaccording to claim 1 wherein R² is COOR⁶.